(1) Field of the Invention
The present invention relates to a polyvinyl chloride resin composition which gives a molded article having an excellent impact resistance, solvent resistance and transparency.
(2) Description of the Related Art
Since a polyvinyl chloride resin is cheap and has various excellent chemical and physical properties, this resin is manufactured in large quantities than other synthetic resins and is widely used in various fields. Nevertheless, as is well-known, a molded article composed solely of a polyvinyl chloride resin has a problem in that the molded article is brittle under impact, and accordingly, many improvements have heretofore been proposed for overcoming this problem.
As the most effective process for modifying a polyvinyl chloride resin, a process is known in which a graft polymer obtained by graft-polymerizing a monomer such as styrene, acrylonitrile or methyl methacrylate onto a rubbery elastomer is incorporated in a polyvinyl chloride resin (see, for example, U.S. Pat. Nos. 4,362,845, 4,607,080 and 4,624,987, and Japanese Unexamined Patent Publication No. 58-152039). The graft copolymer obtained by the above process has already been marketed as an impact resistance-improving material for a polyvinyl chloride resin and has made a great contribution to a widening of the applications of a polyvinyl chloride resin product.
Nevertheless, the impact resistance is still unsatisfactory in some applications, and a further improvement thereof is desired.
In general, the impact resistance and solvent resistance can be improved by increasing the size of rubber particles in the polymer as the modifier. In this case, however, the problem of a reduction of the transparency arises.
As apparent from the foregoing description, a polyvinyl chloride resin composition having a satisfactory impact resistance, solvent resistance, and transparency has not been developed.